The present invention relates to electrical plug assemblies, and more particularly to an electrical plug assembly having a plug housing including a printed circuit board mounted therein, and spring-loaded contact terminals mounted on the printed circuit board to provide an electrical connection between the prongs of the plug housing and the circuit on the printed circuit board.
Modern portable electronic devices, such as cellular phones, typically are powered by a DC power source, usually delivered by rechargeable batteries installed in the device. Plug assemblies, such as plug chargers, are typically used to couple these portable electronic devices to an AC power source in order to provide the required voltages to recharge the batteries. Various non-portable electrical devices typically are powered only from an AC power source, usually delivered through a plug connected to a wall receptacle or socket, but require that this AC power be converted into the required DC voltages for powering these devices. Electrical plug assemblies, such as plug adapters, are often used to convert the AC power to provide the required DC voltages to these electrical devices. The modern technology trend is towards higher density and lower profile electrical devices. A common disadvantage of known plug assemblies is that these assemblies are bulky and inefficient in the use of available space. There is thus a need to optimize the packaging size of plug assemblies used with electrical devices.
Plug assemblies typically include a body portion and a plug housing having an electrical plug for enabling the plug assembly to be connected to an AC power source through a wall receptacle or socket. Electrical plugs throughout the world include various configurations of AC prongs or pins (hereinafter referred to as prongs) that extend outwardly from the plug housing and are shaped to enable electrical and mechanical connection to the AC wall receptacle or socket. Various plug housings provide a mounting for the AC prongs which creates a hollow portion or cavity within the plug housing. The European plug standards CEE 7/16 and EN50075, for example, specify the use of an extended plastic base to house a portion of the AC prongs, thereby creating a hollow cavity portion. Various known plug assemblies, such as plug chargers for electrical devices having batteries, house circuitry usually mounted on a printed circuit board (PCB) positioned within a body portion. Typically, flexible wires are used to electrically couple the AC prongs to the circuit on the PCB. A drawback of such plug assemblies is that the cavity of the plug housing is not used to house this circuitry, or to reduce the amount of circuitry mounted on the PCB positioned in the body portion.
For plug assemblies that include a plug housing having a cavity portion, the body portion is bulkier than necessary and space is wasted within the plug housing. As a consequence, the packaging size of such plug assemblies is not optimized and the material cost is higher than necessary.
In addition, known means of providing electrical contact between the AC prongs and the circuit on a PCB to be powered by the AC power source is through the use of flexible wires, extended copper springs, or the direct soldering of the prongs to the PCB. The use of such wires, springs, or direct soldering makes assembly more difficult than necessary. What is needed is a structure that creates a secure electrical and mechanical contact between the AC prongs and the PCB within the plug assembly that can be assembled quickly and easily and which optimizes packaging size and reduces the plug assembly""s profile. What is also needed is a structure that allows the PCB electrical contacts to be closer to the AC prongs in order to further optimize packaging size.
The present invention solves the above identified problems of known devices by providing a plug assembly wherein a PCB is located in the hollow portion of the plug housing and the AC prongs are electrically connected to the PCB using spring loaded contacts mounted on the PCB.
Broadly stated, the present invention is directed to a plug assembly including a body portion and a plug housing connected thereto and having a plurality of AC prongs extending therefrom shaped to enable the plug assembly to be connected to an AC female outlet, the plug housing providing a mounting for the plurality of AC prongs and creating a cavity in the plug housing, the plug assembly comprising a first printed circuit board mounted in the plug housing and extending into the cavity, and a pair of contact terminals mounted on the first printed circuit board, each contact terminal in a predetermined position so as to create a spring-loaded electrical contact with a corresponding one of the AC prongs.
In one embodiment of the present invention, the first PCB is mounted to the body portion of the plug assembly. For a second embodiment, the plug assembly has a second printed circuit board mounted in the body portion operatively connected to the first printed circuit board. For a third embodiment, the first printed circuit board has one portion mounted in the body portion and a second portion mounted in the plug housing. In anther embodiment of the plug assembly of the present invention, a second printed circuit board is mounted in the body portion and extended into the plug housing, wherein the first printed circuit board is operatively connected to the second printed circuit board. In yet another embodiment, a second printed circuit board is mounted in the body portion, wherein the first printed circuit board extends into the body portion and is operatively connected to the second printed circuit board.
The present invention also provides a preferred and two alternate contact terminals, any of which can be used with any of the plug assembly embodiments described herein. The present invention also provides a corresponding method for assembling the plug assembly.
The present invention reduces the bulkiness, optimizes the packaging size, and reduces the profile of the plug assembly by using the hollow area of a plug housing to house a PCB having components mounted thereon, thereby providing a reduction or elimination of the need to mount components within the body portion of the plug assembly. A further advantage of the present invention is that it eliminates the need to use flexible wires, springs, or direct soldering between the AC prongs and the circuitry on the PCB, thereby making assembly of the plug assembly quicker and easier through use of a spring loaded contact terminal. A further advantage of the present invention is that it reduces the overall material cost of the plug assembly as a result of the optimized packaging size.